Studies will be continued on the cellular patterns and activities occurring during in vitro palatal elevation. Statistical analyses of cell density and isotopic labelling patterns will be completed. These analyses will provide a model system for the changes in cell patterning and activities which occur in the shelves during palatal elevation. Agents such as chlorcyclizine and azaserine which are known to influence the synthesis or degradation of extracellular matrix components will be used in combination in vivo-in vitro experiments. The morphological effects of altering these shelf components will be examined.